How often do you charge your phone?

Typically, a modern phone battery's (lithium-ion) lifespan is 2 – 3 years, which is about 300 – 500 charge cycles as rated by manufacturers. After that, the battery capacity will drop by roughly 20%. 

How often you charge will affect the battery life, for better or worse. In short, the more often you top up your battery, the better. To REALLY minimize battery degradation, top up for every 10% drop in battery level. And keep your battery level as close to the middle (50%) as possible. Impractical and unrealistic, yes they are. But these are only for maximizing battery health.